Hello everyone, we generally work on tractors but have a 287B Cat with electrical issues to diagnose. Serial number ZSA00530. The story was, over a period of time the park would have sporadic issues. Now it's a no go. When the key is turned on, all the lights on the dash light up, it starts as typical but then all the lights go off including the park light. The park switch works because the hydraulic remote function works with that. There's no way to make the machine move at all at this point. If anyone has advice to give, that would be swell. I'm feeling the need to get service manual, wiring diagram, etc. around so I at least have something to go off of. But here's a specific question... what should the voltage be at the seat bar switch. I've got 8 volts, and thought it should be 12v but then I wasn't sure. Will do some more testing, but thought I'd just post to see if there's helpful feedback. Thanks in advance!
Also, could someone give specific details on where exactly is the park brake solenoid? I was getting conflicting advice on which one it is.
There is a long thread on diagnosing a park brake/non-moving B-Series Skid Steer that probably has all the information you need. It also has a copy of the RENR6419 electrical schematic that suits your Serial Number, so win-win. Click this LINK to go straight to it. The armrest switch is a double function switch. The common terminal is connected to machine frame ground. The Interlock Control monitors the state of the other two terminals (NO & NC). It needs to see one of them with continuity to ground while at the same time the other one should be open circuit. When the switch changes state the terminal that previously had continuity to ground must now be open circuit, and the one that was previously open must have continuity to ground, if that makes sense. Also one wire passes through the "operator present" switch in the seat cushion in order to disable the drive system when nobody is sitting in the seat whatever position the armrest switch is in. It mounts into Manifold #1. 2nd illustration gives more detail.
Thanks Nige, that's got me headed the right direction.
Hello, I'm back on this thread again, meaning I haven't fixed the electrical issue with this 287B yet. Here's the deal... I'm almost sure the interlock ecm is bad, but I wish I had a way to know for certain. I've checked power and ground to the ecm, seems good. If I manually power the park brake and pilot solenoids the machine functions like normal, so that checks out. Here's how the machine acts: the seat bar and presence switch circuit is working fine because they affect if the machine will start, like normal. The dash lights will come on when started, to test like normal, and then all of them will go off, including the park and seat lights. I guess that could simply be that the interlock is saying its a no go. If I disconnect ground to interlock ecm those lights will come on, but i just figured that was from backfeeding somehow. The wiring harness generally seems to be in good condition. It seems like I've gone over everything I can think of. Now I just need someone to tell me the ecm is bad! We have the Cat software and cord, and the software can recognize the auxiliary ecm but says its unsupported... I haven't had much experience with the software. Any ideas? I'm tempted to build a wire circuit, tie it into the seat switch, and have a rocker switch on a relay with keyed power that will fire the 3 solenoids that will allow everything to function.
That will do you no good as far as troubleshooting the Interlock Control is concerned, because it does not communicate with ET. How about posting a photo of your Interlock Control, especially around the electrical connector.
The plug on the module is nice and clean, after I used alot of electrical contact cleaner to get all the hydraulic oil out. No corrosion in the plug. I took the module apart, there was a bunch of aluminum corrosion in the bottom, but I couldn't visibly see any corrosion on the actual board. I resealed it all up nice.
I would strongly suggest that you perform all the wiring tests listed in the thread I linked earlier, making sure that all your measurements fall into the "acceptable" category along the way. If those tests show nothing then the only conclusion which can be arrived at, bearing in mind that you have already tested all the Interlock Control outputs, is that the Control is fubar.
Hello again. For the record, I bought an interlock ecm off eBay for this 287B, plugged it in and the machine works perfect.
Thank you for confirming what I suspected. Unfortunately the fix would not have been cheap but at least you gave all functionality restored.